Heat recovery unit



FIG. 1 is a perspective view of the heat recovery unit embodying the design of the present invention;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a side elevational view thereof;

FIG. 5 is an opposite side elevational view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom view thereof. 

The ornamental design for a heat recovery unit, as shown and described. 